Most people are going to say with short speaker cable runs as you have, there should be no noticeable difference.
But is the difference you are hearing possible, Yes ? Your 11g speaker wire is going to have less resistance than your 16g wire. Most of the time it should not make a difference . Yet when your factor in your speakers impedance of 6ohm and the rise and fall on that impedance during playback at different frequencies. It is possible to hear a difference. Whether most people could tell a difference or not, that's up for debate.
However there is no need or real benefit going from your current 11g to 10g, neither a perceivable or measurable difference.
Bottom line is, I think it's all system dependent, as far as with your amplification and speakers as to whether or not there is an audible difference or not. If you and your wife can hear a difference, stick with what sounds best to the both of you.
Don't let others opinions that might tell you it's all a placebo effect or you can't hear a difference make your decision. Even if it is a placebo effect (i'm not saying it is), if that effect is what you like, stick with it.
Dont forget the number one rule in audio. Everybody has their own opinions, but the only one that really matters is what sounds the best to you.